1. Field of the Invention
The present invention relates to a composite electronic component using a sintered body that is formed by firing a plurality of ferrite layers as an integral unit, and more particularly to a composite electronic component in which a magnetic circuit forming portion and an antistatic circuit portion are constituted in the sintered body.
2. Description of Related Art
With the widespread use of high-speed serial communication, a common-mode choke coil adaptable for a high-frequency range is demanded. ICs used in the high-speed serial communication are generally vulnerable to static electricity. Accordingly, those ICs need to be protected against static electricity. From that point of view, a composite component is demanded which includes the common-mode choke coil and a static electricity protection element in an integral unit.
Patent Document 1, listed blow, discloses a composite electronic component illustrated in an exploded perspective view of FIG. 11. In the disclosed composite electronic component 1001, a common-mode filter layer 1002a and an antistatic element layer 1002b are sandwiched between first and second magnetic substrates 1001a and 1001b. The common-mode filter layer 1002a includes spiral conductors 1003a and 1003b. The spiral conductors 1003a and 1003b are magnetically coupled to each other. The antistatic element layer 1002b includes gap electrodes 1004 and 1005, and a varistor layer 1006 covering the gap electrodes 1004 and 1005.
The spiral conductors 1003a and 1003b are each formed on an insulating layer by the thin-film forming method.
In the composite electronic component 1001, a magnetic ferrite layer is arranged between insulating layers in the common-mode filter layer 1002a. Furthermore, plural insulating layers are stacked in the antistatic element layer 1002b. 
On the other hand, Patent Document 2, listed below, discloses a composite electronic component in which a magnetic ferrite layer and a multilayer varistor layer made of ZnO are stacked and fired as an integral unit.
Furthermore, Patent Document 3, listed below, discloses a composite electronic component in which a magnetic ferrite layer including a coil conductor made of a thick film and a multilayer antistatic portion made of ZnO are stacked with a stress relaxation layer interposed therebetween, and they are fired as an integral unit.